Human-machine interfaces that are used to translate human movements to machine movements are used in myriad industries. For example, some aircraft flight control systems include a human-machine interface in the form of one or more hand or foot user interfaces. The user interfaces, or inceptors, are typically configured to be disposed in a null position and the flight control system, in response to input forces supplied to the user interface from the pilot that move the user interface from its null position, controls the movements of various aircraft flight control surfaces. No matter the particular end-use system, the human-machine interface preferably includes some type of haptic feedback mechanism back through the interface to the interface operator. These haptic feedback mechanisms may be implemented using active devices, passive devices, or both.
Haptic feedback mechanisms may, among other functions, supply a force that urges the user interface, when moved from the null position, back toward the null position. Haptic feedback mechanisms also typically supply various tactile cues to the user. For example, many haptic feedback mechanisms implement one or more “soft stops” at one or more user interface positions relative to the null position. More specifically, when the user interface is moved from the null position to a soft stop position, the haptic feedback mechanism may supply an increased feedback force to the user interface. As a result, the user may need to supply an increased amount of force to the user interface to further move the user interface beyond the soft stop position. Moreover, in some implementations it may be desired to supply different force magnitudes to the user interface depending on the direction in which the user interface is being moved. For example, it may be desirable to supply a greater force magnitude when the user interface is being moved in one direction than when it is being moved in another direction. In the context of the above-mentioned aircraft user interfaces, it may be desirable to supply a greater force magnitude when the user interface (or inceptor) is being moved in an inboard direction than when it is being moved in an outboard direction.
Presently, the above-mentioned haptic feedback functions, namely soft stops and differing force feedback magnitudes for differing directions of motion, have been implemented using active devices. More specifically, by actively controlling a motor coupled to the user interface. It is becoming increasingly desirable, however, to implement various user interfaces, such as pilot inceptors, with passive haptic feedback mechanisms. Yet, there are presently no known passive feedback mechanisms that readily implement soft stops and differing force feedback mechanisms for differing directions of motion.
Hence, there is a need for a user interface passive haptic feedback mechanism that implements soft stops and differing force feedback mechanisms for differing directions of motion. The present invention addresses at least this need.